Biological cells form basis of every living organism consists on Earth. The number of cells can range from just a single one (bacteria, amoeba) up to 150 trillion (Elephant). These cells contain a number of different components. Some of the most important components are proteins. Being linear polymers of amino-acids, they are folded into specific compact structures and facilitate important functions such as energy production, signal transduction, protein trafficking, molecular transport, and also host-pathogen interactions.1 An important class of proteins are membrane proteins. These proteins are embedded into anisotropic lipid bilayers at the cell boundaries, where they can be used for the interaction of the cell with the "outer" world. Be it the transport of nutrients across the membrane or signal transduction, they can handle everything. Membrane proteins have a large hydrophobic area. This area is normally located within the hydrophobic core of the membrane formed by lipid acyl chains. Hydrophobic interactions allow the protein to integrate into the membrane and to acquire the correct structure. Due to the complex environment at the membrane interface, most membrane proteins need some help with folding and positioning inside the membrane. For this insertases are used. In E.coli there are two complexes used for this: YidC and SecYEG. This is also because it is in itself a membrane protein so it cannot be analyzed outside of a membrane. In a membrane vesicle the exact number and composition of proteins is unknown. The size and shape of the vesicles can differ greatly and it is possible for interactions to occur that can normally not be seen. Also it is hard to analyze both sides of a protein at once since most synthetic bilayers form micelles2. The SecYEG complex has seen extensive research but YidC is still relatively unknown. is why the structure and mechanism of YidC is still largely unknown. This is true for most membrane proteins. Normally detergents are used to extract membrane proteins. However, this unnatural environment may destabilize and/or dissociate protein complexes and render the protein non-functional1. This makes analytical methods relying on detergent micells very unreliable.
To combat this difficulty a solution has been found. A nanodisc is a small disc of a mixture of lipids surrounded by a scaffold protein to keep the layer intact. This size can be controlled and is homogeneous is shape. A nanodisc (Reference) can imitate a normal membrane while still allowing single molecule analysis. In the following sections more will be explained about YidC, Nanodiscs and the research preformed to incorporate a YidC protein in a nanodisc.